The objectives of the core component are three-fold: to provide central- ized facilities for mass spectrometric analyses and oligodeoxynucleotide synthesis, to support a seminar series for invited speakers to discuss related research with Program members, and to provide administrative support for participants in this Program. Mass spectrometry plays a critical role in the analysis of exocyclic structures and synthetic intermediates; furthermore, a important new component, the LC/MS thermospray system, is being added to our current mass spectrometry facilities. Placing this aspect of the research in the core facility will ensure that it is freely available to investigators in the Program. Synthesis of oligodeoxynucleotides is essential for several Projects; this can most effectively be accomplished by a centralized service facility.